Opened 6 years ago
Closed 6 years ago
#20361 closed defect (fixed)
PPL backend resolves the problem every time get_variable_value or get_objective_value is called
Reported by:  mkoeppe  Owned by:  

Priority:  major  Milestone:  sage7.2 
Component:  numerical  Keywords:  lp 
Cc:  dimpase, vdelecroix, jdemeyer  Merged in:  
Authors:  Matthias Koeppe  Reviewers:  Dima Pasechnik 
Report Upstream:  N/A  Work issues:  
Branch:  df42b5b (Commits, GitHub, GitLab)  Commit:  df42b5b74f30f1fca6a7c236c933c83b434f6f3e 
Dependencies:  Stopgaps: 
Description
The PPL backend sets up a new PPL problem and resolves it from scratch every time that get_variable_value
or get_objective_value
is called.
sage: p = MixedIntegerLinearProgram(solver='ppl', maximization=True) sage: x = p.new_variable() sage: p.set_objective(p.sum((i+20)*x[i] for i in range(1000))) sage: p.add_constraint(p.sum((i+15)*x[i] for i in range(1000)), max=20000) sage: x.set_max(1) sage: p.solve() # takes a few seconds 11438750/507 sage: p.get_objective_value() # takes a few seconds, should be instant 11438750/507 sage: p.get_values(x) # takes forever, should be instant
Change History (5)
comment:1 Changed 6 years ago by
comment:2 Changed 6 years ago by
 Branch set to u/mkoeppe/ppl_backend_re_solves_the_problem_every_time_get_variable_value_or_get_objective_value_is_called
comment:3 Changed 6 years ago by
 Commit set to df42b5b74f30f1fca6a7c236c933c83b434f6f3e
 Status changed from new to needs_review
New commits:
df42b5b  Fix for #20361: PPL backend resolves the problem every time get_variable_value or get_objective_value is called

comment:4 Changed 6 years ago by
 Reviewers set to Dima Pasechnik
 Status changed from needs_review to positive_review
Great!
comment:5 Changed 6 years ago by
 Branch changed from u/mkoeppe/ppl_backend_re_solves_the_problem_every_time_get_variable_value_or_get_objective_value_is_called to df42b5b74f30f1fca6a7c236c933c83b434f6f3e
 Resolution set to fixed
 Status changed from positive_review to closed
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oh, great catch, I was always wondering why get_values is so bloody slow with ppl...